A desktop stapler normally includes a lower base portion and a main body pivotally attached to the base. The body pivots toward the base in normal use as the stapler handle is pressed to eject a staple from the staple track. A striker urges a staple out of a staple exit location toward an anvil, where the anvil is immediately under a stack of papers to be fastened together. The anvil bends the legs of the staple so that the legs clinch behind the papers. It is important that the striker remain aligned with the anvil, being neither too much in front nor too rearward of the anvil. Misalignment of the striker and anvil prevents the staple from forming correctly behind the papers since the legs bend forward or rearward where it is desired only that the legs be bent toward each other.
Such a defective curl or formation of the staple behind the stack of stapled papers renders the staple unsuitable for its intended purpose of fastening the papers together. The user must then somehow unfasten the defective staple and re-staple the stack. Uncurling, detaching or withdrawing the defective staple from the stack is time consuming and an irritation, often requiring use of a staple puller, a bladed tool to slide underneath the staple to pry it loose, or finger pinching manipulation. It is at the very least a nuisance to fix a defective staple and is undoubtedly a waste of productive time.
Typically the stapler body is pivoted from a position above the base. As the body arcs downward about the pivot into position just above the anvil to eject a staple, the staple exit location underneath the striker translates rearward in relation to the anvil.
In particular, in a conventional stapler, the translating motion of the striker is rearward as the body moves toward the base since the pivot point is above the level of the base. An analogy is to look at the hands of a clock. If the minute hand is at the 3 o'clock position, the pivot point and the pointer of the hand are horizontally at the same level, but once the hand is pointed toward the 2 or 4 o'clock positions, the horizontal distance of the pointer of the minute hand to the pivot point has shortened as compared to the 3 o'clock position. Through basic trigonometry, if the distance from the pivot point to the striker is radius R, and the angle between the horizontal position of the body and the downward stapling position of the body is θ, then the horizontal distance x that the striker translates toward the pivot point is x=R−(R)(cos θ). On the other hand, if a stapler were designed with the pivot position at or below the level of the base, then the striker translates forward as the body moves toward the base.
Another alignment consideration is the vertical distance between the striker and the anvil at the beginning of the arcuate movement of the body. If the stapler is of small capacity, such as for stapling less than 20 pages, the amount of striker rearward translation is not significant if the pivot location is not too far above the base. However, in the case of a larger capacity stapler, such as 60 pages, the highest and lowest stapling positions of the body in relation to the anvil are quite different. If the position of the pivot is relatively high above the base, the rearward translation component of the arcing motion is further increased. Consequently, it is desirable to have a mechanism in a stapler that can closely maintain the striker to anvil alignment in spite of the front to rear translating motion and regardless of the paper capacity.